Force responsive switch



United I States Patent 3,518,384 FORCE RESPONSIVE SWITCH James A. Carley, San Pedro, Leonard H. MeRoskey, Los

Angeles, and Robert Q. Parsons, San Gabriel, Calif.;

said Leonard H. McRoskey assignor of one-half to John W. McRoskey and Catherine McRoskey Filed Oct. 30, 1967, Ser. No. 679,098 Int. Cl. H01h 35/14 U.S. Cl. ZOO-61.45 12 Claims ABSTRACT OF THE DISCLOSURE A vibration sensitive switch having a pair of terminal electrodes sealed in the base end of a sealed envelope of glass preferably containing an inert gas, One electrode having a one turn coil formed at its free end to provide a ring contact, and the other electrode having an elongate coiled spring secured at one end thereto, this spring extending through the ring and having its free end positioned beyond the ring, and a bridging bead of glass inwardly spaced from the base to rigidly interconnect and hold the electrodes.

BACKGROUND OF THE INVENTION The present invention relates to electric circuit makers and breakers.

Heretofore, vibration sensitive switching devices for closing electrical circuits, such switches being commonly referred to as tremble or trembler switches, have in general employed a cantilevered mounted spring with a weight on its outer end, this weight providing a movable contact adapted upon spring deflection to engage a surrounding fixed ring contact. Such devices have in the main been quite large, and often too large for mounting in many of the small confined spaces in which it is sometimes desired to use this type of switch. Also, such known prior constructions were relatively costly and diflicult to produce in quantity with dependable and consistent operating characteristics which could be maintained over extended periods of time.

In seeking to overcome these and other disadvantages of the prior art devices'having a construction as noted above, there was disclosed in US. Letters Patent No. 2,996,586 a Magnetic Tremble Switch having a body of the order of one inch in length in which a rod between a pair of magnets is supported by the magnets in spaced relation to annular contact members adjacent the ends of the rods.

In the present invention, many of the problems and' undesirable inherent operational difiiculties including complexity of construction and fabrication, as well as size limitations of the noted prior art devices, have been overcome. As exemplary of the size, the structure of the present invention has been embodied Within an envelope having dimensions of the order of .625 inch in length and .2 inch in diameter.

SUMMARY OF THE INVENTION The present invention relates generally to electric circuit switching devices, and is more particularly concerned with electric switches which are extremely sensitive to actuating forces including mechanical vibrations which may result from an external source or movement of the switch from its normal position.

It is one object of the invention to provide a small, rugged trembler type force responsive switch of simple construction, which may be fabricated economically, which has long life, and which has salient built-in dependable operating characteristics.

3,518,384 Patented June 30, 1970 A further object is to provide a switch of the above character which is relatively impervious to changes in environmental surrounding media, temperature, and the like.

Another object is to provide a switch of the herein described character in which the design and construction of the operative components is such as to facilitate fabrication changes by slightly varying the relative positions of the components to meet specific required values of actuating force.

It is also an object to provide a switch of this character which is selectable for operation and response to forces of different value, depending upon whether the switch is vertically or horizontally disposed.

Briefly these and other objects are accomplished by supporting a vibratable movable contact on a base electrode, this contact being in the form of an elongate coiled spring which extends through a single turn helix in the form of a ring associated with another base electrode, these electrodes being bridged by a bead of glass in spaced relation to the base, and the base forming a part of a glass enclosing envelope preferably containing an inert gas such as argon.

Further objects and advantages of the invention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing several embodiments of the invention without placing limitations thereon.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the accompanying drawings, which are for illustrative purposes only:

FIG. 1 is an enlarged longitudinal section of a switch according to the present invention, certain components being shown in elevation for clarity;

FIG. 2 is a transverse section through the same, taken substantially on line 22 of FIG. 1;

FIG. 3 is a fragmentary view showing the relationship of the contact elements when the switch has its longitudinal axis vertically disposed;

FIG. 4 is a similar view showing the relationship of the contact elements when the longitudinal axis of the switch is horizontally disposed; and

FIG. 5 is a View similar to FIG. 1, of a modified embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more specifically to the drawings, for illustrative purposes, the invention in one form is shown as embodying an elongate generally cylindrical envelope 10 of glass or other suitable material formed to provide a main cylindrical body portion 11 integrally formed at one end With a thickened base 12 and at its other end with the usual seal off tip 13. As thus constructed, the envelope provides a sealed cavity within which the active elements of the switch are mounted, as will hereinafter be described. This cavity is preferably evacuated and charged with an inert gas such as argon which will keep the switch contacts cleaned, prevent oxidation and in general prolong the life and dependability of the switch.

As clearly shown in FIG. 1, the switch is provided with a pair of electrodes 14 and 15 which are sealed into the base 12. Outwardly of the base, the electrodes project to form terminal connections 16 and 17, while inwardly the electrodes project into the .interior of the envelope to form supports 18 and 19 for the switching elements.

The movable vibration sensitive contact, as generally indicated at 20 is in the form of a coiled spring made from tungsten wire. Although the coils of this contact are disclosed for clarity as being spaced apart, in practice the coils are tightly wound with adjacent coils in engagement. The resilient deflectable spring as thus formed is secured at one end to a deflected end portion 18 which extends towards the adjacent support 19.

The support 19 is shown as being extended axially of the envelope to a position in spaced relation to the deflected end portion 18', where it is deformed to provide a single turn helical coil 21 which in effect forms a ring contact surrounding the coil spring with the longitudinal axis of the spring and the axis of the ring contact being coincident, as shown in FIG. 1. In order to properly center the coil spring within the helical coil 21, a section 19a is angularly deflected away from the end portion 18'. As shown in FIG. 1, the helical coil 21 is positioned substantially midway between the ends of the coil spring. As thus arranged, it will be observed that the coil spring forms in effect a pendulous contact although it does not specifically carry a weight at its free end. By utilizing this construction, the coils of the spring provide through out the length of the spring contact surfaces which are engageable with the helical coil 21, irrespective of the position of the helical coil between the ends of the spring.

As further shown in FIG. 1, there is provided adjacent the end portion 18', a bead 22 which is secured to the supports 18 and 19, that provides a bridging member of insulating material and securely rigidifies the structure and prevents distortion under variable temperature conditions which might tend to decentralize the contact 20 with respect to the helical coil 21. The bead 22 is spaced from the base end 12 of the envelope.

By utilizing a construction as described above, the design of the contacts is such that they may be easily modified in order to meet variable specifications with respect to the gravitational force required to cause closure of the contacts. For example, by providing a helical coil 21 of greater or less diameter, it will require a correspondingly greater or less force to close the contacts. Similarly the amount of closing force required is dependent upon the size mandrel used for winding the spring which is used for the contact 20. It will also be apparent that since the contact 20 is supported in the manner of a cantilever structure, the amount of deflection required to effect closure of the contacts will vary depending upon whether the helical coil is placed more closely to the end portion 18' or more closely to the free end of the contact 20. Having these variable possibilities, the switch con tact components can be readily and easily varied to meet a great variety of force requirements.

It is an additional important feature of the switch of the present invention that the switch is selective as to the amount of force required to close the contacts, depending upon whether the switch is vertically disposed as shown in FIG. 3 or horizontally disposed as shown in FIG. 4. In the vertical position of the switch, the contact 20 will be centrally spaced within the ring contact formed by the helical coil 21 so that radially the annular spacing between the adjacent surfaces of the contacts will be circumferentially the same as indicated at a. Thus by properly arranging the contacts in the manner explaied above, the contacts of the switch will close the contacts upon the occurrence of a vibrational force, for example, of 2G.

Referring to FIG. 4, where the switch is placed in a horizontal position, and with the proper correlation of the contacts as explained above, the contact 20 will normally be off center with respect to the ring contact, and instead of haying the space a between the contacts, this space at the bottom of the ring will be reduced to a/2, while at the top of the ring the space between the contacts will be increased to Thus, if the switch is designed to close at 26 with the spacing at, then with a spacing a/2 the switch will close with a minimum force of 16. A selectivity is thus pro- 4 vided depending upon whether the switch is vertical or horizontal, and also a selectivity is provided according to whether the vibration is in a vertical or horizontal direction.

As an example of a switch designed to close at 2G in the vertical direction and 1G in the horizontal direction, it would involve elements having the approximate characteristics as hereinafter noted. The electrodes would be made of copper coated nickel-alloy known under the trademark name of Dumet having a diameter of .010". The coiled contact would be made of .002" tungsten wire having an outside coil diameter of .014". The helical coil 21 would have one turn and would be wound on a mandrel having a diameter of .031". The length of the coil spring from its secured point at the end portion 18' to the effective contact plane of the helical coil 21 would be .140. As shown, the total length of this contact would be approximately .280", since the ring is substantially at mid-position thereof.

Referring to FIG. 5 there is shown a modified structure of the switch according to the present invention, in which the arrangement of certain parts has been changed somewhat over that illustrated in FIG. 1. Corresponding parts of the previously described and the modified structures have been indicated by the same numerals.

The modified structure diflers primarily in that the end portion 18 has been axially extended in the envelope to includes a portion 18" to which the sensitive contact 20 is connected. Also the section 19a, instead of extending at an angle to the envelope axis, is in this form arranged to extend along and be in contact with the inner wall surface of the cylindrical body 11 of the envelope and has been made slightly longer so as to increase the spacing of the coil 21 with respect to the end portions 18' and 18".

It will be noted further, that the coil 21 and bead 22 have a tight fit engagement with the inner Wall surface of the cylindrical body 11.

The above noted changes as embodied in the modified form of the invention provide a very rigid structural arrangement which has been found to be particularly desirable and beneficial for switches of this character that are to be installed in locations where they may be subjected to relatively high and extreme force operating conditions.

Although the switch of the present invention has in general been described as being responsive to vibrations, it is not to be thus limited, since the switch is sensitive to any force which will deflect the movable contact, for example, inertial forces, centrifugal force, and the like.

From the foregoing description and drawings, it will be clearly evident that the delineated objects and features of the invention will be accomplished.

Various modifications may suggest themselves to those skilled in the art without departing from the spirit of our invention, and, hence, we do not wish to be restricted to the specific forms shown or uses mentioned.

We claim:

1. A switch, comprising:

(a) abase;

(b) a pair of electrode terminals fixedly supported in said base;

(c) a ring contact carried by one of said electrodes in spaced relation to said base; and

(d) a resilient elongate pendulous contact supported against movement at one end on the other of said electrodes with one portion positioned within said ring and extending therethrough, and including means whereby said contact engages said ring upon predetermined deflection thereof.

2. A switch according to claim 1, wherein the pendulous contact has a uniform configuration transversely, and when the switch is vertically positioned will have its longitudinal axis centered within said ring, and upon the switch being horizontally positioned will have its axis more closely spaced to one side of said ring.

3. A switch according to claim 2, wherein the resiliency of said pendulous contact, the spacing between the pendulous contact and the ring, and the position of the ring longitudinally of the pendulous contact are so relatively proportioned that the contacts will engage under a force of 26 when the switch is vertical, and a force of 16 when the switch is horizontal.

4. A switch according to claim 2, wherein the pendulous contact comprises a coiled spring of resilient material.

5. A switch according to claim 4, wherein the coiled spring projects through the ring contact, and has a free end lying on the opposite side of the ring from its supported end.

6. A switch according to claim 2, wherein the ring is integral with said one of said electrodes and comprises at least a one turn coil extension thereof.

7. Aswitch according to claim 1, wherein the electrodes extend from the base in adjacent parallel relation.

8. A switch according to claim 7, wherein the electrodes are bridginly interconnected in spaced relation to said base by a rigid securing member of insulating material.

9. A switch according to claim 8, wherein said securing member comprises a glass bead.

10. A switch according to claim 1, wherein the base includes a sealed envelope around portions of the electrodes extending from said base, the pendulous contact and the ring contact, said envelope containing an inert gas.

11. A switch according to claim 10, wherein the ring contact, peripherally is engaged by an adjacent wall of the envelope.

12. A switch according to claim 10, including a bridging member of insulating material conecting the electrodes adjacent said base, said bridging member having engagement at its periphery with an adjacent wall of the envelope.

References Cited UNITED STATES PATENTS 12/1953 Cockram 200--61.49 XR 8/1960 Goss 20061.49 XR OTHER REFERENCES 

